1. Field of the Invention
The invention relates to a bellows seal assembly and bellows valve equipped therewith, which are mainly applicable to places with height restrictions after the valve is installed.
2. Description of the Related Art
A conventional bellows valve includes a valve body, a bonnet, a packing box, a bellows seal assembly, packing, a stem, and a disc. On the stem inside the valve body is sheathed with the bellows seal assembly, which includes a bellows. One end of the bellows is fixed to the stem and the other end is fixed to the packing box. As shown in FIGS. 1 and 2, to improve the sealing performance and increase the service life, the bellows seal assembly is composed of two pieces of bellows rather than one and the two-piece bellows are welded in series via a lantern ring. In other words, one end of a front bellows 1′ is welded to a packing box 4′ and the other end is welded to a lantern ring 3′ while one end of a rear bellows 2′ is welded to the lantern ring 3′ and the other end is welded to a lower bellows seat 5′ to form the bellows seal assembly. The packing box of the valve is welded to the upper port on the bonnet to form an upper seal and the lower bellows seat 5′ of the bellows seal assembly is welded to the stem to form a lower seal.
Since the bellows seal assembly is composed of two pieces of bellows connected in series, it is relatively long and the matching bonnet neck must be lengthened accordingly, so does the stem. Consequently, on the one hand, material costs are increased, and on the other hand, the length of the whole valve is increased, so does the stroke of the valve switch, thus it is unfavorable for places with height restrictions.